With the rapid development of display technologies, touch screen panels have been widely-used in people's daily life. Currently, touch panels may be classified into an add on mode touch panel, an on cell touch panel and an in-cell touch panel, based on the structural configuration of the touch panels. Among the various touch panels, the add on mode touch panel employs a touch panel and a liquid crystal display (LCD) which are separately fabricated and then bonded together to form a LCD with a touch function. Such an add-on mode touch panel suffers from the disadvantages of high production cost, low transmitivity and thick module. In contrast. An in-cell touch panel embeds touch electrodes of the touch panel inside the LCD, which not only reduces the overall thickness of the module, but also significantly reduces the production cost of the touch panel. As a result, the in-cell touch panel is very popular with panel manufactures.
The currently available capacitive in-cell touch panel is implemented by directly adding a touch scan line and a touch sense line on a conventional Thin Film Transistor (TFT) array substrate. That is, two layers of strip-shape Indium Tin Oxides (ITO) electrodes intersecting each other in different planes are formed on a surface of the TFT array substrate. The two layers of ITO electrodes respectively function as the touch drive line and the touch sense line of the touch panel and an induction capacitor is generated at the non-coplanar intersection of the two ITO electrodes. The functioning procedure of the in-cell touch panel is as follows: when a touch drive signal is applied to the ITO electrode that functions as the touch drive line, a voltage signal coupled through the induction capacitor from the touch sense line is detected. During the procedure, when a human body contacts the touch panel, an electric field of the human body will affect the induction capacitor and thereby change the capacitance of the induction capacitor, which in turn changes the voltage signal coupled from the touch sense line. A position of the touch point is then determined from the change of the voltage signal.
The above in-cell touch panel structure requires two separate drive chips ICs to realize touch driving and display driving respectively and therefore has a high cost.